"""
应用配置管理
支持从环境变量和 .env.dev 文件加载配置
"""
from typing import List, Optional
from pydantic import Field, validator
from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    """应用配置类"""

    # === 应用基础配置 ===
    PROJECT_NAME: str = "FastAPI Demo"
    VERSION: str = "1.0.0"
    DESCRIPTION: str = "A simple FastAPI learning project"
    DEBUG: bool = False
    ENVIRONMENT: str = Field(default="production", description="运行环境: development, testing, production")

    # === 服务器配置 ===
    HOST: str = "127.0.0.1"
    PORT: int = 8000
    WORKERS: int = 1
    RELOAD: bool = False
    LOG_LEVEL: str = "info"

    # === API 配置 ===
    API_V1_STR: str = "/api/v1"
    DOCS_URL: Optional[str] = "/docs"
    REDOC_URL: Optional[str] = "/redoc"

    # === 数据库配置 ===
    # MySQL 数据库配置（从环境变量或 .env 文件读取）
    DB_HOST: str = Field(default="localhost", description="数据库主机地址")
    DB_PORT: int = Field(default=3306, description="数据库端口")
    DB_USER: str = Field(default="root", description="数据库用户名")
    DB_PASSWORD: str = Field(default="", description="数据库密码")
    DB_NAME: str = Field(default="fastapi_demo", description="数据库名称")
    DB_CHARSET: str = Field(default="utf8mb4", description="数据库字符集")
    
    # 数据库连接池配置
    DB_ECHO: bool = False
    DB_POOL_SIZE: int = 5
    DB_MAX_OVERFLOW: int = 10
    DB_POOL_TIMEOUT: int = 30
    DB_POOL_RECYCLE: int = 3600
    
    @property
    def DATABASE_URL(self) -> str:
        """构建数据库连接URL"""
        return f"mysql+pymysql://{self.DB_USER}:{self.DB_PASSWORD}@{self.DB_HOST}:{self.DB_PORT}/{self.DB_NAME}?charset={self.DB_CHARSET}"

    # === Redis 配置 ===
    REDIS_HOST: str = "localhost"
    REDIS_PORT: int = 6379
    REDIS_DB: int = 0
    REDIS_PASSWORD: Optional[str] = None

    # === CORS 配置 ===
    CORS_ORIGINS: List[str] = ["*"]
    CORS_ALLOW_CREDENTIALS: bool = True
    CORS_ALLOW_METHODS: List[str] = ["*"]
    CORS_ALLOW_HEADERS: List[str] = ["*"]

    # === JWT 认证配置 ===
    SECRET_KEY: str = Field(default="your-secret-key-change-in-production", min_length=32)
    ALGORITHM: str = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
    REFRESH_TOKEN_EXPIRE_DAYS: int = 7

    # === 邮件配置 ===
    SMTP_HOST: Optional[str] = None
    SMTP_PORT: int = 587
    SMTP_USER: Optional[str] = None
    SMTP_PASSWORD: Optional[str] = None
    SMTP_FROM: Optional[str] = None

    # === 文件上传配置 ===
    UPLOAD_DIR: str = "./uploads"
    MAX_UPLOAD_SIZE: int = 10485760  # 10MB
    ALLOWED_EXTENSIONS: List[str] = ["jpg", "jpeg", "png", "pdf", "doc", "docx"]

    # === 第三方 API 配置 ===
    OPENAI_API_KEY: Optional[str] = None
    STRIPE_API_KEY: Optional[str] = None
    AWS_ACCESS_KEY_ID: Optional[str] = None
    AWS_SECRET_ACCESS_KEY: Optional[str] = None
    AWS_REGION: str = "us-east-1"

    # === 监控配置 ===
    SENTRY_DSN: Optional[str] = None
    PROMETHEUS_ENABLED: bool = False
    METRICS_PATH: str = "/metrics"

    # === 限流配置 ===
    RATE_LIMIT_ENABLED: bool = True
    RATE_LIMIT_REQUESTS: int = 100
    RATE_LIMIT_PERIOD: int = 60  # seconds

    @validator("ENVIRONMENT")
    def validate_environment(cls, v):
        """验证运行环境"""
        allowed = ["development", "testing", "production"]
        if v not in allowed:
            raise ValueError(f"ENVIRONMENT must be one of {allowed}")
        return v

    @validator("CORS_ORIGINS", pre=True)
    def parse_cors_origins(cls, v):
        """解析 CORS 来源配置"""
        if isinstance(v, str):
            return [origin.strip() for origin in v.split(",")]
        return v

    @property
    def is_development(self) -> bool:
        """是否为开发环境"""
        return self.ENVIRONMENT == "development"

    @property
    def is_production(self) -> bool:
        """是否为生产环境"""
        return self.ENVIRONMENT == "production"

    @property
    def is_testing(self) -> bool:
        """是否为测试环境"""
        return self.ENVIRONMENT == "testing"

    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"
        case_sensitive = True


# 根据环境加载不同的配置文件
def get_settings() -> Settings:
    """获取配置实例"""
    import os
    env = os.getenv("ENVIRONMENT", "development")

    # 优先级：环境特定配置 > .env 通用配置
    env_files = [".env"]
    if env == "development":
        env_files.append(".env.dev")
    elif env == "testing":
        env_files.append(".env.test")
    elif env == "production":
        env_files.append(".env.prod")

    # 尝试加载对应的环境配置文件
    for env_file in reversed(env_files):
        if os.path.exists(env_file):
            return Settings(_env_file=env_file)

    return Settings()


# 全局配置实例
settings = get_settings()